1. Technical Field
The present invention relates to an illumination stabilization apparatus for a vehicle headlamp, which uses a Single Ended Primary Inductance Converter (SEPIC) to stably supply power to a headlamp.
2. Background Art
A vehicle headlamp is a lamp for illuminating the area ahead of a vehicle to ensure safe traveling during periods of low visibility, such as at night. Such a vehicle headlamp must emit light having uniform illuminance in order for the driver to recognize obstacles located ahead of the vehicle and secure a certain range of vision, and for the drivers of oncoming vehicles to travel comfortably. Therefore, stably supplying constant power from a battery to a headlamp has been recognized to be important.
Conventionally, a push-pull converter, a buck-boost converter, etc. are used to stably supply power.
The push-pull converter, as shown in FIG. 1A, includes a transformer T having a center tap on the primary side thereof, two power switches TR1 and TR2 connected to the primary side, full-wave rectifier diodes D1 and D2 connected to the secondary side of the transformer, and an LC filter connected to an output terminal.
The operation of the push-pull converter is briefly described. The push-pull converter is operated such that the two power switches TR1 and TR2 are periodically turned on or off, and thus voltages having a phase difference of 180 degrees are applied.
However, the push-pull converter, which is generally used to control power of 500 Watts or more, is problematic in that it is not suitable for vehicles because it has a large size and generates a large amount of heat.
The buck-boost converter, as show in FIG. 1B, is a DC-DC converter for outputting a voltage higher or lower than a certain input voltage value, and includes a switch TR1, an inductor L1, a rectifier diode D1, and a capacitor C1.
The operation of the buck-boost converter is briefly described. When the switch is in on, an input stage and an output stage are separately operated by the rectifier diode, whereas, when the switch is in off, the influence of input power is eliminated, the inductor L1 is connected to an output load, and the energy stored in the inductor is transferred to the capacitor C1 and the load.
However, the buck-boost converter has problems in that an excessive voltage ripple is generated in the switch at the time of control in a Discontinuous Conduction Mode (DCM), and in that additional passive elements (for example, an inductor) are required at the time of control in a Continuous Conduction Mode (CCM), and thus heat is generated.
The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.